With Apple’s HealthKit platform set to launch in the coming weeks as part of iOS 8, the tech company has updated its privacy policy for health apps, with the new rules warning developers of HealthKit-related mobile software not to sell or share collected personal data to marketers or any similar organizations.

Apple is all set to reveal a new iPhone (or iPhones), and possibly a smartwatch, at a special event in Cupertino on September 9. iOS 8 is expected to launch at the same time, with a slew of new health-related apps from independent developers likely to follow soon after.

HealthKit is an Apple-made application program interface (API) that tracks and gathers data from third-party software for presentation in Apple’s forthcoming Health app. The new app has the potential to show a wide range of user data, including, for example, weight, blood pressure, heart rate, and physical activity. Data can also be delivered via hardware such as Fitbit, or the sensor-laden smartwatch that many expect Apple to unveil alongside its new handsets next month.

While developers will be able to build apps that deliver data to Health, they’ll also be able to pull information from other health-related apps on a user’s mobile device if granted permission.

With this in mind, Apple is keen to ensure that such sensitive information is not sold on or in any way distributed to others. The Cupertino company’s updated policy informs developers they must not “sell an end-user’s health information collected through the HealthKit API to advertising platforms, data brokers or information resellers,” and also should not use collected data for any other purpose than to provide health and/or fitness services.

According to an FT report Thursday, research carried out last year by campaign group Privacy Clearing House revealed that 43 percent of the health apps it looked at shared “personally identifiable information” with marketers.

Apple hopes that by making the rules clear from the start, it’ll be able to avoid privacy-relatedcontroversies further down the road. The move also aims to instill confidence in customers using its products to monitor their fitness and health, an area which is attracting increasing attention from not only app developers but gadget makers, too.